Here's another potentially likely GHash scenario:

• GHash sells most of its available bitcoins for fiat
• GHash achieves 51+% on purpose knowing it will trigger a selloff
• GHash buys back the bitcoins at a greatly reduced price
• GHash points its miners to other pools to alleviate the threat
• Bitcoin price rises again and GHash realizes a large profit from market manipulation

This seems like a low-risk strategy, generates a tidy profit for GHash, and can probably be done several times before the community catches on so long as they wait long enough between runups.

If you believe that they are so beneficent that they would never try anything like this, then perhaps you'd like to buy some shares I have in the Golden Gate bridge for sale?